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Re: the standard rules for assigning types to integer constants in C


On Wed, Aug 22, 2001 at 06:37:34PM +0100, Joseph S. Myers wrote:
> On Tue, 21 Aug 2001, Zack Weinberg wrote:
> 
> > 1: Were these rules different in C89?  If so, what were they?
> 
> They were different in C89:
> 
> 	The type of an integer constant is the first of the corresponding 
> 	list in which its value can be represented.  Unsuffixed decimal: 
> 	int, long int, unsigned long int; unsuffixed octal or hexadecimal: 
> 	int, unsigned int, long int, unsigned long int; suffixed by the 
> 	letter u or U: unsigned int, unsigned long int; suffixed by the 
> 	letter l or L: long int, unsigned long int; suffixed by both the 
> 	letters u or U and l or L: unsigned long int.

Aha.  Thanks, it makes sense now.

> > 2: What, if anything, should we do about this?
> 
> Implement the rules conditional on flag_isoc99 (making sure that something
> appropriate and consistent with ISO 14882 is done for C++) and change
> "integer constant type rules" in c99status.html from "Missing" to "Done".
> Work out what -Wtraditional ought to do in C99 mode if the C99 type is the
> same as the traditional type but different from the C89 type.  No-one
> answered my question <URL:http://gcc.gnu.org/ml/gcc/2000-09/msg00417.html>
> about this, so I left off implementing this feature.

I'm testing a patch now.

In C99 mode, I chose to compare the C99 type with the traditional
type, but issue a -Wtraditional warning if the C89 and C99 types
don't match.  This somewhat widens the scope of -Wtraditional, but
sensibly, IMO.

zw


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